Voltage regulating transformer

ABSTRACT

A voltage regulating transformer for providing a constant output is disclosed. The transformer has a coil connected in series with a capacitor to form a resonant circuit. The transformer is formed of a plurality of laminate members, the members forming a core about which the coil is wound. The other legs of the laminate members form a yoke about the coil. Alternate laminate members are formed with a magnetic gap to provide a plurality of magnetic gaps in the flux path of the coil.

United States Patent 1191 athor Apr. 9, 1974 [22] Filed:

[ VOLTAGE REGULATING TRANSFORMER [75] Inventor: Ramesh P. Rathor, Cincinnati, Ohio [73] Assignee: Foster Transformer Company,

Cincinnati, Ohio Sept. 18, 1972 [21] Appl. No.: 289,767

[52 us. (:1 323/44, 323/60, 336/178, 336/212, 336/234 51 Int. Cl GOSf 1/38, 0051"7/00 58] Field of Search 323/6, 4 s, 60, 61, 44, 323/57; 336/178, 212, 234

[56] References Cited UNITEDSTATES PATENTS 3,745,499 7/1973 Smith 336/160 3,361,934 1/1968 Harland 336/234 X 3,579,088 5/1971 Fletcher et al 323/60 X 2,664,541 12/1953 Henderson 336/234 X 3,585,493 6/l97l Moerlein 323/6l 3,686,561 8/1972 Spreadbury 323/6 3,389,329 6/1968 Quirk et al 323/45 Primary ExaminerGerald Goldberg Attorney, Agent, or FirmJohn G. Schenk 57] ABSTRACT A voltage regulating transformer for providing a constant output is disclosed. The transformer has a coil connected in series with a capacitor to form a resonant circuit. The transformer is formed of a plurality of laminate members, the members forming a core about which the coil is wound. The other legs of the laminate members form a yoke about the coil. Alternate laminate members are formed with a magnetic gap to provide a plurality of magnetic gaps in the flux path of the coil.

14 Claims, 8 Drawing Figures BACKGROUND OF THE INVENTION This invention relates generally to transformers and more particularly to a voltage regulating transformer to provide a constant voltage output.

Numerous voltage regulating devices are known in the art. U. 8. Pat. No. 3,585,493 issued to Herbert Moerlein is an example of prior voltage regulating transformers. An unusual feature of these type transformers is the magnetic gap, either an air gap or nonmagnetic material, extending the entire depth of the transformer. The core members are made of a ferromagnetic material and come in solid bar shapes. This construction limits the usefulness of such transformers in that given sizes only are obtainable. Generally, these transformers are of a somewhat large and bulky size necessitated by the solid type construction.

Accordingly, it is an object of this invention to provide a voltage regulating transformer having great utility.

A further object of this invention is to provide a voltage regulating transformer having a plurality of magnetic gaps to provide saturation and stabilization of the transformer at a lower voltage.

A still further object of this invention is to provide a voltage regulating transformer of simple and economical construction and which uses a plurality of laminate members to provide the yoke and core elements.

Yet another object of this invention is to provide a voltage regulating transformer which can be made of a reduced size yet provides a constant output voltage over a wide range input voltage fluctuation.

And a still further object of the present invention is to provide a voltage regulating transformer which is simple to construct and may be constructed less expensively than voltage regulating devices presently available.

SUMMARY OF THE INVENTION This invention provides an improved voltage regulating transformer for providing a stable output voltage over the wide range of input voltage fluctuation. The transformer is formed with a plurality of laminate members which form the core and yoke portions of the transformer. Alternate laminate members have a magnetic gap therein so as to provide a plurality of mag- BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings show present exemplary embodiments of this invention in which:

FIG. l is a perspective view, partially exploded, illustrating one exemplary embodiment of this invention showing the laminate structure of the transformer;

FIG. 2 is a schematic electrical circuit diagram of the voltage regulating transformer of FIG. ll;

FIG. 3 is a view of the voltage regulating transformer, partly schematic, illustrating the transformer of FIG. 1 in longitudinal section;

FIG. 4 is a view of one laminate member forming a part of the transformer of FIG. 1;

FIG. 5 is a view of the laminate members having a magnetic gap used in combination with the laminate members of FIG. 4 to construct the transformer of FIG.

FIG. 6 is a graph illustrating the saturability of the transformer of this invention;

FIG. 7 is a view taken along line 7-7 of FIG. 3; and

FIG18 is a view similar to FIG. 5 illustrating a laminate member to provide different magnetic gaps.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS Reference is now made to FIGS. l and 3 of the drawings which illustrate one exemplary embodiment of the improved voltage regulating transformer of this invention, which is designated generally by the reference numeral 10. The transformer 10 is provided with a primary coil 12 wound about a coil supporting portion, shown generally as 14, of the transformer core 15. A secondary coil 16 is wound about the primary coil 12. The ends of the primary coil 12 are connected to a pair of input terminals 18 and 20, the latter being connected through a capacitor 22. The ends of the secondary coil 16 are connected to the output terminals 24 and 26. Although the embodiment-herein described is shown to have a primary coil and a secondary coil, it is obvious that a single coil may also be utilized.

The structure of the transformer core canbest be seen by referring to FIGS. 1, 4, 5 and 7. The core 15 is formed of a plurality of first laminate members defining a continuous flux path, and a plurality of second laminate members each having a magnetic gap therein and interposed among the first laminate members to define a composite stacked laminate core having a plurality of laterally spaced magnetic gaps in the flux path thereof. Each laminate member is formed of an E and I element 28 and 30, respectively. Referring in particular to FIG. 4, the laminate member comprises a pair of end elements 30 and 38, with a pair of leg members 32 and 36-and a coil supporting portion 34. More specifically, the E-element has three legs 32, 34 and 36 outwardly extending from an end element 38 into engagement with the I-element or end element 30.

The laminate member shown in FIG. 5 has the same construction as that of FIG. 4 and, accordingly, corresponding structure will be provided with the same numerical designation and not described again. The difference between the laminate members of FIGS. 4 and 5 is that the center leg 40 does not extend outwardly the same distance as the legs 32 and 36. Thus, when the E-element member of FIG. 5 is placed in abutting relationship with the l-element or end element 30, a gap 42 exists between the end of the leg 40 and the I-element 30.

The laminate members are formed from any suitable magnetic material so as to provide a low-reluctance flux path for the flux generated by the coils 12 and 116. The laminate members are stacked in opposed relationship one to the other. In other words, the leg portions extend in opposite directions and the element 38 of one laminate member is aligned with the I-element 30 of the next laminate member. The laminate members are held together by any suitable means, such as nonmagnetic rivets or the like 43 (FIG. 3), extending through apertures 44, 46, 48 and 50 of the E- and I-elements.

Referring in particular to FIG. 7, it is seen that the coil supporting portion, comprised of adjoining legs of 34 and 40, is provided with a plurality of magnetic gaps. The number of magnetic gaps, which in this instance is an air gap, is dependent on the number of laminate members utilized in forming the core 15.

The transformer is intended for service with an alternating current source applied to input terminals 18, 20. The capacitor 22 and primary coil 12 are selected to form a series tuned inductive capacitive circuit as shown in FIG. 2. The output terminals 24 and 26 are magnetically coupled through the secondary coil 16 to the primary coil 12. The effect of a loose coupling between the output and input terminals is described in the aforementioned Moerlein patent. It is sufficient herein to say that a low reluctance flux path is provided in the laminate member shown in FIG. 4 and a region of high reluctance is provided by the laminate member shown in FIG. 5. It has been found that a transformer having the laminate members of this invention providing alternating magnetic gaps (regions of high reluctance) will become saturated at a lower voltage than other transformer core structures. Such a transformer will thus provide a stable output from the secondary coil which is relatively insensitive to fluctuations in the input voltage over a wide range.

Referring in particular to FIG. 6, line 52 represents the capacitor voltage. The curved line 54 represents 'the voltage in a standard transformer not of this invention and the curved line 56 represents the voltage across the primary coil of a transformer made in accordance with the present invention. The Y axis represents output voltage and the X axis represents input voltage. It is seen that curved line 54 flattens out at approximately 1 10 volts input. The flattened out portion would represent a standard transformer having reached a saturation point. Due to the alternating magnetic gaps of high reluctance regions, the transformer 10 of the present invention becomes saturated at a much lower voltage. The transformer reaches the saturation point at approximately 96 volts and the curved line 56 flattens out at this point. At the transformer saturation point, the curve 56 will flatten out along the region designated generally as 57. This part of the curve, i.e., region 57, is the region which controls the flux change in the secondary coil. Hence, should the input voltage increase to 120 volts, the output of the secondary coil would not change due to the saturation of the transformer. It has been found that the regulated output voltage of the transformer of this invention will not vary more than I to 2 percent over the wide range of variation in input voltage. It should be noted, however, the output voltage may be changed by varying the capacitor and coil.

FIG. 8 represents a modification of the laminate member 28 corresponding to the laminate member shown in FIG. 5. The identical elements of the laminate member 28 of FIG. 8 bear the same reference numerals as used in describing the laminate members of FIGS. 4 and 5. In FIG. 8, the E-element has been modified such that the center leg 54 extends outwardly from the end I element 38 a distance sufficient to engage the I- element 30 (leg 54 is equal to leg 34 of FIG. 4). Legs 52 and 56, extending outwardly from end element 38, terminate at a distance short of the I-element 30 so as to provide magnetic gaps 58 and 60. Thus, when the laminate member of FIG. 8 is combined with the laminate member of FIG. 4, a plurality of magnetic gaps is formed in the resulting structure. The resulting transformer in this embodiment provides a constant voltage output as hereinabove described.

While the above described magnetic gaps have been discussed and illustrated as airgaps, it should be noted that nonmagnetic material may be utilized to provide the necessary magnetic gap. It can be seen that a transformer constructed in accordance with this invention will become saturated at a low voltage due to the multiplicity of magnetic gaps formed therein. The output voltage will be regulated within approximately I to 2 percent over the wide range of the input voltage. Accordingly, the objectives hereinbefore set forth have been accomplished.

While present exemplary embodiments of this invention have been illustrated and described, it will be recognized that this invention may be otherwise variously embodied and practiced by those skilled in the art.

What is claimed is:

l. A voltage regulating transformer having magnetic conductivity, comprising a plurality of stacked, interspersed first and second laminate members each having an E-I configuration and together defining a composite, laminated transformer core and yoke, said first laminate members defining a continuous flux path and said second laminate members having a gap in the flux path thereof, thus defining a plurality of laterally spaced magnetic gaps in the flux path of the transformer core, said laminate members defining a coil supporting portion, coil means wound about said coil supporting portion, means connecting said coil means to an input source of alternating current, means connecting said coil means with output terminals, said plurality of spaced magnetic gaps in the flux path of said transformer core providing spaced regions of high reluctance whereby the transformer becomes saturated quickly thereby providing a constant output over a wide range of input fluctuation.

2. A voltage regulating transformer as in claim 1, wherein each laminate member comprises a pair of spaced, substantially parallel end elements, said coil supporting portion extending from one end element toward the other end element substantially intermediate the ends thereof, and a pair of leg elements on either side of and parallel to the coil supporting portion and extending between the end elements adjacent the opposite ends of the end elements, said coil wound around the coil supporting portion between the coil supporting portion and the leg elements.

3. A voltage regulating transformer as in claim 2, wherein the coil supporting portion on each of said second laminate members is shorter than the leg elements and is spaced from said other end element to define said magnetic gap, said leg elements engaging said other end element.

4. A voltage regulating transformer as in claim 2, wherein the leg elements on each of said second laminate members are shorter than the coil supporting portion thereof and said leg elements are spaced from the other end element to define a pair of magnetic gaps in the flux path thereof.

5., A voltage regulating transformer as in claim ll, wherein a capacitor is connected in series with said core between the core and the input source thereby forming a series-resonant circuit.

6. A voltage regulating transformer as in claim 1, wherein said laminate members each comprise an E- element and an I-element, said E- and I-elements engaging one another to form the magnetic circuit of the transformer.

7. A voltage regulating transformer as in claim 6, wherein each E-element includes an end element and three leg elements extending laterally therefrom, the middle leg element comprising said coil supporting portion and being spaced from the l-element to define said magnetic gap.

3. A voltage regulating transformer as in claim 6,

wherein each E-element includes an end element and.

three leg elements extending laterally therefrom, the middle leg element comprising said coil supporting portion, the leg elements on either side of the coil supporting portion spaced from the I-element to define a pair of magnetic gaps.

9. A voltage regulating transformer as in claim 6, wherein the first and second laminate members are stacked in alternating relationship with alternate laminate members reversed so that the I-element of a first laminate member is adjacent an end element of a second. laminate member.

10. The voltage regulating transformer according to claim 1 in which said first and second laminate members are alternately stacked to form said composite laminate transformer core.

11. A voltage regulating transformer having magnetic conductivity comprising in combination a plurality of first laminate members each defining a continuous flux path, a plurality of second laminate members interspersed among said first laminate members and each having a magnetic gap in the flux path thereof, said first and second laminate members being stacked together to form a composite laminated transformer core having a plurality of laterally spaced magnetic gaps in the flux path of said stacked laminate transformer core wherein the magnetic gaps provide regions of high reluctance whereby the transformer becomes quickly saturated to provide a constant output over a wide range of input fluctuation, each of said laminate members including a pair of spaced, substantially parallel end elements, a pair of leg elements and a coil supporting portion extending between said end elements, coil means wound about said coil supporting portion, means connecting said coil means to an input source of alternating current including a capacitor connected in series with the coil and with the source to form a series resonant circuit, and means connecting said coil means with output terminals.

12. A voltage regulating transformer as in claim 11, wherein said laminate members each comprises an E- element and an l-element, each said E-element including one end element and three leg elements extending laterally therefrom, said coil supporting portion comprising the middle of said leg elements, said other end element comprising the l-element, said E- and elements engaging one another to form the magnetic circuit of the transformer, and said coil supporting portion on said second laminate members being shorter than the leg elements on either side thereof and spaced from the I-element to define said magnetic gap.

13. A voltage regulating transformer as in claim ll, wherein said laminate members each comprises an E- element and an l-element, each of said E-elements including one end element and three leg elements extending laterally therefrom, said coil supporting portion comprising the middle of said leg elements, said other end element comprising the I-element, said E- and I-elements engaging one another to form the magnetic circuit of the transformer, said leg elements on either side of the coil supporting portion of the second laminate members being shorter than the coil supporting portion and spaced from the l-element to define a pair of magnetic gaps in the flux path of the second laminate member.

14. The voltage regulating transformer according to claim lll in which said first and second laminate members are alternately stacked to form said composite transformer core. 

1. A voltage regulating transformer having magnetic conductivity, comprising a plurality of stacked, interspersed first and second laminate members each having an E-I configuration and together defining a composite, laminated transformer core and yoke, said first laminate members defining a continuous flux path and said second laminate members having a gap in the flux path thereof, thus defining a plurality of laterally spaced magnetic gaps in the flux path of the transformer core, said laminate members defining a coil supporting portion, coil means wound about said coil supporting portion, means connecting said coil means to an input source of alternating current, means connecting said coil means with output terminals, said plurality of spaced magnetic gaps in the flux path of said transformer core providing spaced regions of high reluctance whereby the transformer becomes saturated quickly thereby providing a constant output over a wide range of input fluctuation.
 2. A voltage regulating transformer as in claim 1, wherein each laminate member comprises a pair of spaced, substantially parallel end elements, said coil supporting portion extending from one end element toward the other end element substantially intermediate the ends thereof, and a pair of leg elements on either side of and parallel to the coil supporting portion and extending between the end elements adjacent the opposite ends of the end elements, said coil wound around the coil supporting portion between the coil supporting portion and the leg elements.
 3. A voltage regulating transformer as in claim 2, wherein the coil supporting portion on each of said second laminate members is shorter than the leg elements and is spaced from said other end element to define said magnetic gap, said leg elements engaging said other end element.
 4. A voltage regulating transformer as in claim 2, wherein the leg elements on each of said second laminate members are shorter than the coil supporting portion thereof and said leg elements are spaced from the other end element to define a pair of magnetic gaps in the flux path thereof.
 5. A voltage regulating transformer as in claim 1, wherein a capacitor is connected in series with said core between the core and the input source thereby forming a series-resonant circuit.
 6. A voltage regulating transformer as in claim 1, wherein said laminate members each comprise an E-element and an I-element, said E- and I-elements engaging one another to form the magnetic circuit of the transformer.
 7. A voltage regulating transformer as in claim 6, wherein each E-element includes an end element and three leg elements extending laterally therefrom, the middle leg element comprising said coil supporting portion and being spaced from the I-element to define said magnetic gap.
 8. A voltage regulating transformer as in claim 6, wherein each E-element includes an end element and three leg elements extending laterally therefrom, the middle leg element comprising said coil supporting portion, the leg elements on either side of the coil supporting portion spaced from the I-element to define a pair of magnetic gaps.
 9. A voltage regulating transformer as in claim 6, wherein the first and second laminate members are stacked in alternating relationship with alternate laminate members reversed so that the I-element of a first laminate member is adjacent an end element of a second laminate member.
 10. The voltage regulating transformer according to claim 1 in which said first and second laminate members are alternately stacked to form said composite laminate transformer core.
 11. A voltage regulating transformer having magnetic conductivity comprising in combination a plurality of first laminate members each defining a continuous flux path, a plurality of second laminate members interspersed among said first laminate members and each having a magnetic gap in the flux path thereof, said first and second laminate members being stacked together to form a composite laminated transformer core having a plurality of laterally spaced magnetic gaps in the flux path of said stacked laminate transformer core wherein the magnetic gaps provide regions of high reluctance whereby the transformer becomes quickly saturated to provide a constant output over a wide range of input fluctuation, each of said laminate members including a pair of spaced, substantially parallel end elements, a pair of leg elements and a coil supporting portion extending between said end elements, coil means wound about said coil supporting portion, means connecting said coil means to an input source of alternating current including a capacitor connected in series with the coil and with the source to form a series resonant circuit, and means connecting said coil means with output terminals.
 12. A voltage regulating transformer as in claim 11, wherein said laminate members each comprises an E-element and an I-element, each said E-element including one end element and three leg elements extending laterally therefrom, said coil supporting portion comprising the middle of said leg elements, said other end element comprising the I-element, said E- and I-elements engaging one another to form the magnetic circuit of the transformer, and said coil supporting portion on said second laminate members being shorter than the leg elements on either side thereof and spaced from the I-element to define said magnetic gap.
 13. A voltage regulating transformer as in claim 11, wherein said laminate members each comprises an E-element and an I-element, each of said E-elements including one end element and three leg elements extending laterally therefrom, said coil supporting portion comprising the middle of said leg elements, said other end element comprising the I-element, said E- and I-elements engaging one another to form the magnetic circuit of the transformer, said leg elements on either side of the coil supporting portion of the second laminate members being shorter than the coil supporting portion and spaced from the I-element to define a pair of magnetic gaps in the flux path of the second laminate member.
 14. The voltage regulating transformer according to claim 11 in which said first and second laminate members are alternately stacked to form said composite transformer core. 